Can a cyclohexane be cis if it has 3 substituents?

[saveourpens]

...if cyclohexane has 2 of the 3 substituents facing the same direction, would it be called a cis? ,,,ok found out that cis- trans nomencleture doesnt go beyond 2 substituents.

now that still means 1-chloro-4,4-dimethylcyclohexane can have two conformers right? because in one the Cl would be axial and in the other it would be equatorial.

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[AugustWinterMan]

If cyclohexane was substituted, then the R-S naming system would be used.

Cis/Trans is the nomenclature used to describe unsaturations. However, if you are actually talking about cyclohexene, then you need to use the E/Z nomenclature with the Cahn-Ingold priority rules because you would be dealing with the carbon skeleton of the ring in addition to the sustituents, not simple hydrogen (assuming substitution is on the double bond).

Does this help?

 

[saveourpens]

thanks, I think its more simple than that though .

basically, if you have a cyclohexane with 2 methyls on carbon 4 (one facing towards you the other facing the other way) and a chlorine attached to carbon 1, would it be called cis1-chloro-4,4-dimethylcyclohexane or just 1-chloro-4,4-dimethylcyclohexane.

I think its just 1-chloro-4,4-dimethylcyclohexane, yet it has two confermers because in one the chlorine is in the axial position and in the other it is in the equatorial position. These two conformers have different relative energies. Yet, I thought that if two cyclohexane confermers differ in engergy I thought they must be cis?

 

[AugustWinterMan]

Well, here is the wikipedia article. I think it would be hard to use the cis/trans reference when you have two methyl groups on 1 carbon.

http://en.wikipedia.org/wiki/Cis-trans_isomerism

 

[saveourpens]

phew that cleared it up for me thanks!

 

[GypsyRhapsody]

If carbon four has two of the same substituents than you cannot have cis/trans isomers, however, you can have conformers, you can always ring flip. The two methyls on carbon four with occupy an axial and an equatorial position. The Chlorine would probably go equatorial b/c methyls Cl have no Pi bonding potential. Be careful with halogens, I know Bromine prefers axial positioning most of the time, not sure about chlorine.